Method of and apparatus for conditioning air



Aug. 2, 1949. c. L. RINGQUIST ,3

METHOD OF AND APPARATUS FOR CONDITIONING AIR Filed Jan. 15, 1947 ,Eig.d

Patented Aug. 2, 1949 UNI TED STATES PATENT *OIFFTCE 2,477,826 TMETHODor AND APPARATUS'T'GR coNnrrroNme am Glaren'ee -L. Ringquist, La Crosse,Wis.,; as signor to The lrane Company La Crosse, Wis.

amification "January '15, 194i, Se'rial No. 722124; 8 Claims. (01.62'-6) This invention relates to a'n air conditioning apparatus,or-sysiim, particularly adapted to condition the air 'ih a deem to a lpredetermined dew pointand to Jprovide forthe ad'dition .of apredetermined anteater outsideair for'ventilation, with means-forregulalting theamount'of mbisture in the outs'ide air.

"One obj ct of m'y invention is to int'roduce into theroomaipredetermined amount 'o'f outsideair for ventilation purposes andto prevent-the introduction of varying amountsof outside air.

Another object of-myiiriveiition is to treat the outsidehir's'parafewandreuuc'e it t'oa predeterimined :dew rpoint i i e mixing it withrecirtcul-ated or room air.

An the :obie' ei my in enti n ri to p ovi e a novel oo ns meanserdehumid fy n the a r before-mixingjt with therecirculated air; whichwill be at a different dew point than theoutside Another object 10f, myinvention is to provide means -for conditiening the recirculated air, toprovide apredetermined-dewpoint:and to providemeans-foreqnditioningthenutsideair-to a differen-t dew point and mixing*thereoircula-ted air and outside air in predetermined amounts to securea third dewepoint below a predetermined oint i a The above andotherobjects of my invention will be -apparent inthe-followingspecification and drawings, wherein: n

Fig. -1 shows diagrammatically the apparatus used in my invention. I I rV Fig. 2 'shows an end view -:of the longitudinal heat exchanger.

Fig. 3 showsacross sectional view of the longitudinal heat exchanger.

Referring to Fig. 1,15 represents the room or space "tobeeonditibrred,fwherein "outside air is vdrawn int'9theiiiiletjfiloy'meansiof a 'fan i2 isiqiiijr" gage variet and whichdraws" the apparatus in a preand "the outside "air is thendeterhiiriedamo passed through alongitudinal fin coil 24,acrossseeuon-or'one tr te-e demerits 4s or which is ure-1 e 2.

The app ratusemmed'ajcasmg"compo e of Theta" ii heat exchange mediiii'nto the 2 the pulley iii, belt ljfigp'ull'ey -'2il, attached to Shaft -2l on which "are mounted fans t2 "and 16.

The recirculated'air is pulled from theroom "25 into the apparatusthrough the *coil 2 2, "through inlet 34, and'emits irom th'e" coil='22"into themix- -'-ing chamber l5,wher'e itmikes with the outside airwhich enters the 0011 2 4 at and 'leaves the coil z l'at 23.

-Referring to Fig. *2 and :Fig. 3 :an --ei'em'ent 48 of the longitudinalfin -coi1 :24 ;is shown as composed of a longitudinal casing 43, with aconduit therein ifljfo'r thence-*0: heat exchange fluid, and between theeasing 43am the 'cond'uit hl are interposed heat exehange iins 46 whichprovide 'air passages '45 htwen 'the easing "43 and the conduit 44.

Theoutside 'ortiitilhtiiig air is drawn: into the 'unitthroughtheBphifigQZB, communicating with the outside air, ana'the amountof air 'is controlled by "a damper 21 together with thefan l2 whichhandles a preueterimneu'amount of air.

The outside air fthefnis passed through the dehumidifyi'ng confluent itsinto the mixing chamber 15 where it is mixed'fwith the recirculated air"which enters the unit 'itlirough the inlet 36 'a'nd iiajssesthfoug htlie pdil The coil -22 is supplied iivith heat exchange mediumfromth'epipe35, 'ii1whieh'there is interposed a valve 38,-eoritrolli'rig the supply of the doil'ZZ.

The valve 38 iseo itr'oll'ed'byla Hry'bulb thermostat 39 throu'ghtheline ifljflsofth'at 'theamount of work performed by the "coil 2f 2wil1fb1e responsive to the dry 'bulb temperature in "the r'o'o'm "25.

a predetermined temperaturey the thermostat ,39 causesthevalve38*toiepen,' andthe'heat exehange medium from pipe'35 by-passes thecoil 22 and leav s'the apparat hrijii'gh 'i' tiifn pipeBB.

The c-eil 2 is s'upp1ied with heat exchange fluid from the pi'pe -'3l.c'oiine'dted' with the pipe 3! is a by-pass pipe 42 whiohconne cts witha pipe 35 which is connected'with'thevalved-Band the pipe 31. Interposedin'the by-pass 42 is a valve 32 which is responsive'toa humidostat 33situated in the room -25, *whi'ch -'humidostat, through a line M, willcontrol theaoperationof the valve 32 which controlsthe amount of flow ofheat exchange fluidthrough'thecoilikbecause when the valve isopen'tlie'flow will be through the 'bypass instead ofthrdugNthecoiI;thiis' the amount of work performed by'the'eoil -M'is controlledresponsive to the amount or *in'oisture in theroo'm 25. so that'ineffe'ct, the 'coil 24 will remove from the outside air sufilcientmoisture so that when mixed with the recirculated air the, latent loadrequirements will be satisfied.

Assuming that the ventilation requirements of three people in the roomare 199.8 lbs. per hour of outside air, and it is desired to maintainthe inside air conditioned at 80 dry bulb and 67 Wet bulb, it isapparent that there are required to be removed from the recirculated airthe moisture equivalent to the latent load of the people in the room,and that there will also be required to be removed from the outside aira predetermined amount of moisture as to enable the mixture to meet therequired moisture requirements.

The former air conditioning systems have been directed to mixing theoutside air and the recirculated air and then conditioning the mixture,and due to the variations in the amount of moisture in the outside air,it has been found that this is impractical and the results wereunsatisfactory amounts of moisture in the resultant air due to thevarying amounts of moisture in the outside air, consequently theapparatus and method disclosed in this invention is directed toconditioning the outside or ventilating air to such a predeterminedmoisture content as will take care of the assumed latent load in theroom and further to condition the recirculated air substantially withoutthe removal of moisture but to remove a sensible heat therefrom so thatwhen the recir- 3510 (grs. per hr. to be removed) 199.8 (amount ofoutside air) :178 grams per pound of air to be removed to maintain apredetermined moisture content of 78 grains per pound.

78 grs.17.8 grs.=60.2 grs. per pound which corresponds to the moisturecontent per pound of air with 53 dew point. Thus, the outside airleaving the coil 24, at 23, must have a temperature of 53 saturated.Inasmuch as this leaving temperature of the outside air is lower thanthe temperature of the recirculated air, it is evident that the outsideair will remove a small amount of sensible heat from the recirculatedair.

The sensible heat available for cooling below the predetermined dry bulbis then- 199.8 (lbs. of air for ventilation) X024 (specific heat of air)80 (predetermined D. B. temp.) 53 (leaving temp. of ventilated air)=1280 B. t. u. per hour, subtracting this amount 1280 B. t. u. from 8250(total B. t. u. sensible load): 6970 B. t. u. per hr. load to be removedby the recirculated air when passing through the recircuculated air iscombined with the outside air the lated air coil, and

6970 B. t. u. per hr. to be removed by recirculated air coil 0.24(specific heat of air) X1730 (lbs. of air to be emitted into room-199.8lbs. of ventilated air) 19 resultant air will have a predetermined drybulb. temperature difference, and 80 (predetermined For example: assumea typical office space with dimensions 14 x 16' x 11 high and exposed bytwo sides and roof, with three occupants, and with the outside air at 95dry bulb, 78 wet bulb, containing 116 grains of moisture per pound ofair and a desired inside air condition of 80 dry bulb, 67 wet bulb andcontaining 78 grains per pound of air. According to engineering datathere would be a sensible heat gain of 6000 B. t. u. due to transmissionlosses and 2250 B. t. 11. due to internal heat additions from lights andpeople, or a total of 8250 B. t. u. heat gain. Also, according toengineering data, an internal latent load of 525 B. t. u. due to people.

The ventilation requirements for three people at the rate of 15 C. F. M.per person would be 45 C. F. M., which is equal to 199.8 pounds of airper hour. A further assumption is the dry bulbtemperature of the mixedair entering the room should not be lower than 60.

8250 (sensible load in B. t. u.)

which is the total amount of sensible cooling performed by the mixedoutside and recirculated air. The other equation referred to the latentload is:

525 B. T. U. (latent load) X 1050 (latent heat of water) 7000 (gr. perlb.)=3510 grs. per hr.

to be removed from the water on account of the latent load, and

dry bulb air temperature)-19==61 air leaving recirculated air coil,thus, 199.8 lbs. of ventilated air is mixed with 1529.2 lbs.recirculated air to obtain 1730 lbs. of air emitting from the unit intothe room.

Mixing 1529.2 lbs. of recirculated air at 61 dry bulb and havingmoisture content of 78 grains per pound, with 199.8 lbs. of outsidedehumidified air at 53 dry bulb temperature and with a moisture contentof 60.2 grains per pound, produces a final condition of the mixture of60.1 dry bulb temperature and a moisture content of 75.95 grains perpound, which will maintain in the room, conditioned air of 80 dry bulband with a moisture content of 78 grains per pound.

Under the present type of units where the outside air and recirculatedair are mixed before conditioning, mixing 199.8 lbs. of 95 dry bulb and116 grains of moisture per pound outside air with 1529.2 pounds of 80dry bulb and 78 grains of 1730 pounds of air per hour moisture per poundresults in a mixture of 81.4" dry bulb and 82.3 grains of moisture perpound, and from the coil curve this could be conditioned to 61 dry bulbwith a moisture content of 75.95 grains of moisture per pound, which isthe desired condition.

However, assume the outside conditions to vary so that the outside airdrops to dry bulb with 117 grains of moisture per lb. and the insideconditions to be maintained at 80 and 78 grains of moisture per pound aspreviously. The required dry bulb temperature of the mixed air tomaintain 80 would be 69.8, and the air mixture would be 199.8 pounds of35 dry bulb air with 117 grains of moisture per pound and 152912 poundsof 80 dry bulb air with 78 grains of moisture per pound, resulting in acondition of 808 dry bulb with 82 am ss grains of moisture per pound; Inorder toreduce this. mixture to the desired moisture'content of 75.95grains per pound, it would be necessary to reduce the dry bulbtemperature to 64 accord ing to thecoil curve, WhiCh'lS 5.8 below thedry bulb temperature necessary to maintain the desired temperature andwouldresult in undercooling the room. Also, if the dry bulb temperatureof the mixed air wasreducedonly to 69.8 then the moisture content, wouldbe 77 grains per pound, which would not be enough to absorb the latentload in the room and the humidity would be too high. L

Assume the same conditions with the outside air taking care of thelatent load as disclosed herein:

I-Ieat' gains are: I 2000 Transmission taccording 2250 Internal Sensibleheat engineering 525 latent data The required dry bulbleavingtemperature of the mixed air is 69.8 .from the following equation4250 (sensible load B. t. u.) 1730 (lbs. of air, mixed) X 0.24 specificheat of air and 80--10.2=69.8

The desired moisture content is 78 grains per pound of air as before andto maintain this condition the mixed air must have a moisture content of75.95 grains per pound, which is 2.05 grains per pound (the latent load)less than the desired moisture content of the room air.

The outside air is reduced to 53 saturated as before, resulting in amoisture content of the conditioned outside air of 60.2 grains perpound.

The sensible heat available for removal by outside air is 1280 B. t. u.The total sensible heat load of 4250 B. t. u. is therefore reduced by1280 B. t. u. which leaves 2970 B. t. u. sensible heat to be removed bythe recirculating coil. The temperature of the air leaving therecirculating coil would be 71.85 dry bulb as shown by the followingequation:

-808.15=71.85 dry bulb, which will produce a mixture of 697 dry bulbwith a moisture content of 75.95 grains per pound, which is the desiredcondition. It is obvious from the foregoing example that the method ofhaving the outside or ventilating air take care of the latent load andthe recirculated air regulating the dry bulb temperature, possessesdistinct advantages over the method of mixing the outside air andrecirculated air to a mixture which is then conditioned.

It is apparent from the foregoing that I have invented a new and novelmeans of conditioning the air in a room, set forth in the followingclaims, in which I claim:

1. A method of air conditioning a space com prising movingapredetermined amount of outside air in parallel fluid flow heatexchange relationship with a heat exchange fluid, moving air from saidspace into heat exchange relationship with a heat exchange fluid, thenmixing said outside air and said air from the space, and moving themixed air into the space.

2. A method of air conditioning a space comprising moving a heatexchange fluid through a first heat exchanger and then through a secondheat exchanger, moving outside air into parallel fluid flow heatexchange relationship with the heat exchange fluid in said first heatexchanger, moving air from said space into heat exchange relationshipwith the heat exchange fluid in said second heat exchanger, then mixingsaid outside air and said air from said space and then moving the mixedair into the space.

3. Apparatus for air conditioning a space comprising means for moving apredetermined amount of outside air in parallel fllllld flow heatexchange relationship'with a heat exchange fluid, means for moving airfrom said space into heat exchange relationship with a heat exchangefluid, means for mixing said outside air and said air from said spaceand means for moving the mixed air into the space. I 4. Apparatus forair conditioning a space comprising a first heat exchanger having meansfor conducting heat exchange fluid and means for conducting air in heatexchange relationship with said means for conducting heatexchange'fluid, said means for conducting heat exchange fluid and saidmeans for conducting air'being substantially parallel with each other,means for moving outside air through said means for conducting air, asecond heat exchanger, means for moving air from said space through saidsecond heat exchanger, means for mixing said outside air leaving thefirst heat exchanger with said air from said space leaving said secondheat ex= changer and means for moving the mixed air into the space.

5. Apparatus for air conditioning a space comprising a plurality ofconduits for conducting a heat exchange fluid, a plurality of ducts witheach duct surrounding one of said conduits and being of such a size asto provide a passageway for air between said duct and said conduit, heattransfer fins in said passageway, said fins extending longitudinally ofthe conduit and the duct, means for moving outside air through saidducts, a heat exchanger, means for moving air from said space throughsaid heat exchanger, means for mixing said outside air leaving saidducts and said air from said space leaving said heat exchanger and meansfor moving the mixed air into the space.

6. Apparatus for air conditioning a space comprising a first heatexchanger having liquid conduits with a supply and a discharge openingand conduits for conducting air, said liquid conduits and said airconduits being constructed and arranged for parallel flow of liquid andair, a second heat exchanger, a conduit connected at one end to thedischarge opening of the conduit of said first heat exchanger and at theother end to said second heat exchanger for conducting liquid dischargedfrom said first heat exchanger to said second heat exchanger, means formovin outside air through said first heat exchanger, means for movingair from said space through said second heat exchanger, means for mixingsaid outside air leaving said first heat exchanger and said air fromsaid space leaving said second heat exchanger and means for moving themixed air into said space.

7. Apparatus for air conditioning a space comprising a first heatexchanger, a second heat exchanger, means for conducting a heat exchangefluid first through said first heat exchanger and then through saidsecond heat exchanger, a first by-passing means for conducting the heatexchange fluid around said first heat exchanger, humidity responsivemeans in said space for controlling the operation of said firstby-passing am ss means, a second Icy-passing means for conducting. theheat exchange fluid around said second heat exchanger, a temperatureresponsive means in said space for controlling the operation of saidsecond by-passing means, means for moving outside air through said firstheat exchanger, means for moving air from said space through said secandheat exchanger, means for mixing the air from said first heat exchangerwith the air from said second heat exchanger and means for moving themixed air into said space. a

8. Apparatus for air conditioning a space comprising a casing having afirst inlet opening for admitting outside air, a second inlet openingfor admitting air from said. space, a mixing chamher, and an outletopening in the casing for discharging air from the mixing chamber intosaid space, a first heat/exchanger having air ducts arranged todischarge air into said mixing chamber, a conduit leading from saidfirst inlet opening to said first heat exchanger, a fan in said conduitfor moving air in said conduit, a fan mounted in said mixing chamber atthe outlet 8. opening, for, discharging; air from, said mixing chamberinto said space, means mounting said fansona common axis of rotation, asecond heat exchanger atthe second inlet opening, the second heatexchanger having air ducts arranged in a direction normal to the airducts of said first heat exchangertdd-ischargeair in'a direction normalto, the. direction of ,the air stream from said first heat exchanger;

CLARENCEL. RINGQUIST.

REFERENCES CITED The following refererrces are of record in the file ofthis patent:

